Strange black dots with Nvidia privative driver - MGA 2

Hi!, I have a problem with the video.
The problem started when I installed the Nvidia propietary drivers. When I rebooted, I see some black dots in the top left corner, and when I put the cursor near to the black dots, their dissappear, but if I put away the cursor, the black dots come backs.
Any ideas?
This is a screenshot of the problem:

Charlie
The problem started when I installed the Nvidia propietary drivers. When I rebooted, I see some black dots in the top left corner, and when I put the cursor near to the black dots, their dissappear, but if I put away the cursor, the black dots come backs.
Any ideas?
This is a screenshot of the problem:

Charlie